Creative Grids Non Slip 30 Degree Triangle Ruler
Sew together 12 triangles to create a complete circle; 6 to create a half-circle; or 3 to create a quarter-circle. Make pieced arcs and circles up to a finished size of 38 inches. This 19 1/2" 30 degree triangle includes 30 degree, 45 degree, and 60 degree angles.